Skip main navigation

Understanding expiry dates

Expiry dates cause food waste. This is a plain old fact. To understand why, we need to go back to when it all started. Let's explore.

Back to when expiry dates began

In 1972, Marks & Spencer started to print ‘sell by dates on the packaging of perishable food as an indication of freshness. They were extremely proud of their invention, so much so they made a marketing campaign about it, including a TV commercial that became very popular.

Soon, other supermarkets followed the idea in order to show the quality of their products to their customers. As more supermarkets adopted this marketing trick, the government became aware of its benefits and decided to make it mandatory.

The 1979 EC Labelling Directive required date of minimum durability on a pre-packaged foodstuff although a list of selected items such as fresh fruits and vegetables, alcoholic beverages, or fresh pastries was exempt from the obligation.

The legislation was not fully thought through

You’re probably wondering what’s wrong with this? The fact is, the government simply introduced legislation for something that most retailers were already doing anyway and the problem was that it was not fully thought through.

Nowhere in the original legislation, nor in the current EU legislation do they regulate how these dates should be calculated. The other issue is that while the law has not changed since its introduction, its meaning has.

Expiry dates were originally devised as quality indicators. Now they are considered as safety tools.

How does that cause food waste?

How does that cause food waste? Think about all the times you look through the products on the supermarket shelf to find the one with the latest expiry date.

Nearly everyone does that. But what do you think happens to the products with a shorter remaining shelf-life? Now think about all the times you find products past their expiry date in your fridge, either because your eating plans changed or simply because it was hidden at the back and you forgot it.

How many times have you thrown those away without even checking if they were still edible? The examples are countless and have devastating consequences: about 60% of the food wasted in the UK could have been consumed, reported WRAP [2] who have identified opportunities to make simple and safe changes throughout the supply chain to pass on more product life to consumers, saving 250,000 tonnes of waste food by extending product life by just one day.

Best before and use-by dates

Do you know the difference between the ‘best before’ and the ‘use by’ dates? Most people do not [3]. Here’s the difference:

  • the ‘best before’ date is an indication of quality. When the date is passed, it doesn’t mean that the food will be harmful, but it might begin to lose its flavour and texture.
  • the ‘use by’ date is an indication of safety. The product should not be eaten after the date has expired.

Display until and sell by

As well as these two date marks, you might find a ‘display until’ or ‘sell by’ date on some packaging.

These are simply means of communication between the manufacturer and the retailer and the information is now often encoded so as not to confuse consumers.

In Grant Baldwin and Jen Rustemeyer’s documentary, ‘Just Eat It: A Food Waste Story’, Dana Gunders explains that the confusion around these dates leads to 60% of consumers throwing food away prematurely.

And, many producers feed this complexity by using quality measures to set the ‘use by’ date. For instance, ‘use by’ dates for vegetables and meats, both highly-perishable products, are often set on colour, appearance and odour, all sensory aspects which are usually not directly related to safety [1].

Why are the dates not used as intended?

Given that we know all this, why are these dates not used as intended? Why is the product often still edible even past the ‘use by date? Manufacturers have always been risk-averse about date setting because their liability is at stake.

They calculate the durability of their products through lab research not only for scenarios in which the product is correctly handled from beginning to end but also for worst-case scenarios in which they assume everything that could go wrong does go wrong.

This results in a buffer of up to 14 days (depending on the product) between the date displayed on the packaging and the date when the product will actually be unsafe to eat (or will have lost quality for the ‘best before dates).

One example of this in the opportunities WRAP identified is sliced ham where the buffer can be up to 5 days. And it’s interesting to note that there has never been a court case on an expiry date issue, which indicates that expiry dates are overly cautious.

Should we be less cautious about expiry dates in order to reduce waste?

Should we be less cautious about expiry dates in order to reduce waste then? Absolutely not. The safety of the consumer must remain a priority.

What we need is to make use of today’s knowledge and technologies to improve the situation. Some innovators are working on new labelling systems that are more accurate than expiry dates to help reduce waste.

Will the knowledge you’ve gained in this Step change how you use ‘best before’ and ‘use by’ dates in the future? Please share your thoughts in the comments section below.


  1. Expiry Dates: a Waste of Time? Soethoudt J.M., Van der Sluis A.A., Waarts Y., Tromp, S. Wageningen UR Food & Biobased Research 978-94-6173-481-5. 2013.
  2. Courtauld Commitment 3: Delivering action on waste. WRAP.
  3. Section 3 of the flash Eurobarometer report on food waste and date marking.
© EIT Food
This article is from the free online

From Waste to Value: How to Tackle Food Waste

Created by
FutureLearn - Learning For Life

Reach your personal and professional goals

Unlock access to hundreds of expert online courses and degrees from top universities and educators to gain accredited qualifications and professional CV-building certificates.

Join over 18 million learners to launch, switch or build upon your career, all at your own pace, across a wide range of topic areas.

Start Learning now